The demand for smaller electronic components has been strong in recent years in response to the development of more densely mounted electronic circuits for use in mobile phones and other digital electronic devices, and consequently multi-layer ceramic capacitors that constitute these circuits are rapidly becoming smaller in size and larger in capacity.
The capacity of a multi-layer ceramic capacitor is directly proportional to the dielectric constant of the material used for the dielectric layers constituting the capacitor and also to the number of dielectric layers, and inversely proportional to the thickness of one dielectric layer. This means that, to meet the demand for smaller size, the dielectric constant of the material must be raised, thickness of the dielectric layer reduced, and number of dielectric layers increased.
To meet the aforementioned demand for smaller size (such as reducing the thickness of the dielectric layer to 3 μm or less) and larger capacity, attempts have been made to improve the dielectric constant of the dielectric porcelain composition that constitutes the dielectric layers of the multi-layer ceramic capacitor.
Ways to improve the dielectric constant include to bake the materials for secondary constituents beforehand and then add the baked powders to the material for the primary constituent to increase the dispersibility of secondary constituents, as well as to add secondary constituents as individual oxides and then adjust them to specified compositions to achieve a higher dielectric constant (Patent Literatures 1 and 2).
However, these approaches, although leading to a higher dielectric constant, present problems such as causing other characteristics to drop, especially when the composition ratios of secondary constituents are changed for the purpose of improving the dielectric constant. Accordingly, the method of producing desired segregation and thus controlling the solid solution states of added elements is employed to improve the dielectric constant without causing other characteristics to drop.
To meet the demand for smaller size/larger capacity, a greater number of thinner layers must be laminated, as mentioned above, in addition to improving the dielectric constant. In Patent Literature 3, MgTiO3 is added to the dielectric layer-forming material to produce a segregation phase containing Mg and Si so as to improve the dielectric constant, as a way to improve the dielectric constant without causing other characteristics to drop.